1. Field of the Invention
The invention relates to a method for reducing particle emission of an internal combustion engine over its service life, as well as to an engine controller.
2. Description of the Related Art
With internal combustion engines there is generally a problem in that with increasing engine running time, in other words with increasing aging of the engine, higher particle emissions occur. This is at least partially due to the fact that the cylinders, due to symptoms of aging such as carbonization, are filled with a small amount of combustion air during an intake cycle. It is known to reduce particle emissions of internal combustion engines by performing a post-injection, whereby during the ignition cycle in a cylinder an additional fuel injection is performed after or during the actual torque-effective combustion. According to a first, however disputed theory, this post-injection causes soot particles to be created in the combustion chamber of the cylinder, which are discharged into the exhaust pipe to burn up into ash. According to a second theory, the exhaust gas temperature is raised due to the post-injection, thus making particle reduction in subsequent exhaust gas treatment more efficient.
It is disadvantageous that post-injection be carried out continuously over the entire service life of the internal combustion engine, as this leads to increased wear and tear of fuel injectors, making premature replacement of the same necessary, and resulting in shortened service life of the engine.
What is needed in the art is a method which makes it possible to reduce the particle emission that increases during the service life of an internal combustion engine, and at the same time keeps the wear and tear on the injectors as low as possible. Also needed in the art is an engine controller that is suitable for implementation of such a method.